Points in breps issue

I have 4 breps (rectengular plates in the images) and 588 points, and I want to find all the points that in any of the 4 breps.

If I flatten brep tree,“Points in breps” give me correct points: 4 points, each one in one brep;

But if flatten points tree, “Points in breps” give me three points, none of them in the brep

why flattening points tree doesn’t work?

By flattening points you are searching all the points in each brep. But then the list you are culling is the unflattened list of points. You should flatten the input L of cull pattern also so you use the cull pattern of each brep over the entire list of points per each brep, this way you will be left with the points remaining for each brep.